{"id":"F2006B10927","name":"AD/JETSTREAM/57 - Tail Unit De-Icing System","slug":"ad-jetstream-57-tail-unit-de-icing-system","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56470,"registerId":"commonwealth-F2006B10927-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/JETSTREAM/57 - Tail Unit De-Icing System","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nBritish Aerospace BAe 3100 (Jetstream) Series Aeroplanes\n\nAD/JETSTREAM/57 Tail Unit De-Icing System 1/93\n\nApplicability: All Model 3100, and All Model 3200 up to and including constructors number 969 and constructors number 971.\n\nRequirement: Action in accordance with BAe Jetstream Mandatory ASB 30-A-JA 920444.\n\nCompliance: Part 1: Within 150 hours time in service after 7 January 1993, and thereafter at intervals not to exceed 150 hours time in service until Part 2 or 3, as applicable, is accomplished.\n\nPart 2 or 3: Prior to 30 April 1993.\n\nBackground: The manufacturer has determined that the possibility exists for water to become entrapped in the tail unit de-icing system. If sufficient water has collected, ice can form in cold conditions which could restrict or prevent the air flow, causing unsatisfactory operation of the tailplane de-icing boots.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete airworthiness directive with a narrow, specific safety purpose — addressing a known defect in a particular aircraft type's de-icing system. It has not expanded beyond its original technical safety intent."},"complexity_factors":["Single, specific technical requirement referencing an external manufacturer bulletin (BAe Jetstream Mandatory ASB 30-A-JA 920444)","Limited applicability — only specific aircraft models and serial number ranges affected","Simple two-stage compliance structure (repetitive inspections followed by terminating action)","No defined terms section, no cross-references to other legislation beyond the enabling Civil Aviation Regulations 1998","Straightforward conditional logic: inspect repeatedly until fixed, then stop inspecting"],"plain_english_summary":"This is an **airworthiness directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific British Aerospace Jetstream aircraft.\n\n**What it does:**\nOrders owners and operators of certain Jetstream 3100 and 3200 model aircraft to inspect and fix a problem with the tail unit de-icing system. The manufacturer found that water can get trapped in this system. In cold weather, this water can freeze into ice, blocking airflow and stopping the de-icing \"boots\" (inflatable rubber strips on the tail that crack ice off) from working properly.\n\n**Who it affects:**\n- Owners and operators of **all Model 3100** Jetstream aircraft\n- Owners and operators of **Model 3200 aircraft** with serial numbers up to and including 969, plus serial number 971\n\n**What must be done:**\n- **Part 1:** Inspect the system within 150 flight hours after 7 January 1993, then re-inspect every 150 flight hours until the permanent fix is done\n- **Part 2 or 3:** Complete the permanent repair or modification before 30 April 1993\n\n**Why it matters:**\nDe-icing systems are critical for safe flight in cold conditions. If ice builds up on the tail (tailplane), it can disrupt airflow, reduce control, and potentially cause loss of control of the aircraft. This directive prevents that by forcing operators to check for water intrusion and fix the design flaw."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD's scope as written targets specified BAe Jetstream models and constructor number ranges to address the manufacturer-identified risk of water entrapment in the tail unit de-icing system. The actions required (inspection cadence and completion of Parts 2 or 3 by a set date) align with that stated purpose (Applicability, Requirement, Compliance, Background). There is no indication in the text that the AD expands or narrows that stated technical scope beyond those elements."},"complexity_factors":["Narrow technical scope limited to tail unit de-icing system on specified Jetstream serial-number ranges (Applicability).","Mandatory reliance on an external manufacturer's document (BAe Mandatory ASB 30-A-JA 920444) for the technical method (Requirement).","Recurring inspection schedule with a fixed interval (150 hours) until terminal corrective action is done, plus a calendar deadline for completion (Compliance).","Need for operators to arrange maintenance capacity, parts and access to the ASB creates operational coordination complexity despite the AD's short textual length (Requirement, Compliance).","No alternative compliance route or discretionary approvals are set out in the AD text, limiting interpretive complexity but increasing practical rigidity (Requirement, Compliance)."],"plain_english_summary":"This AD requires owners/operators and maintenance organisations of specified British Aerospace Jetstream Model 3100 and 3200 aeroplanes (limited to certain constructor numbers) to follow BAe Mandatory ASB 30-A-JA 920444: start recurring inspections within 150 flight hours and repeat every 150 hours until completing one of two corrective actions, with a final corrective deadline of 30 April 1993.  \n\nIt responds to water entrapment in the tail de‑icing system that can freeze and restrict airflow; operators bear inspection and repair costs."}},"importantCases":[],"_links":{"self":"/api/acts/ad-jetstream-57-tail-unit-de-icing-system","history":"/api/acts/ad-jetstream-57-tail-unit-de-icing-system/history","analysis":"/api/acts/ad-jetstream-57-tail-unit-de-icing-system/analysis","conflicts":"/api/acts/ad-jetstream-57-tail-unit-de-icing-system/conflicts","importantCases":"/api/acts/ad-jetstream-57-tail-unit-de-icing-system/important-cases","documents":"/api/acts/ad-jetstream-57-tail-unit-de-icing-system/documents"}}